here's abc's chief white house correspondent jonathan karl. >> the president referred to the bombing as the event in boston, but make no mistake, the white house is treating this as a terrorist attack. when the president came into the briefing room a short while ago, he vowed to find out who was responsible and hold them responsible. >> we still do not know who did this or why. and people shouldn't jump to conclusions before we have all the facts. but make no mistake, we will get to the bottom of this, and we will find out who did this, we'll find out why they did this. any responsible individuals, any responsible groups will feel the full weight of justice. >> the president said he's directed the full resources of the federal government to help not only with the investigation in boston and the recovery in boston, but also to secure other parts of the united states as necessary. the president was informed of this just minutes after it happened and immediately began to receive briefings from his national security team. we have a photo of the call he had with fbi director muller in the